TOPIC Recent Advances in Reflectarray and Transmitarray Antennas for Space Applications  
AREA Microwave & RF 
SPEAKER Professor Atef Z. Elsherbeni, Dobelman Distinguished Chair and Professor, Electrical Engineering and Computer Science Department, Colorado School of Mines, USA 
DATE 16 September 2014, Tuesday 
TIME 4:00 pm to 5:30 pm 
VENUE E4-04-06, Engineering Blk E4, Faculty of Engineering, NUS 
FEES No Charge 

SYNOPSIS

Mankind has always desired to explore space and bring the solar system within the sphere of his economic influence. This dream that technology will one day allow us to explore our solar system is now becoming a reality. Man has launched satellites and space shuttles all over the solar system and beyond. To communicate with these man-made structures, we rely on high-gain deep-space antenna technology. This advanced technology is rapidly improving and in the recent years, a new generation of antennas has emerged for space communications known as reflectarray/transmitarray.

Deep-space communications requires antennas that can achieve a very high-gain, and to satisfy this requirement most antennas deployed in space have been reflectors or lenses. The common drawback of these antennas however is typically their large volume, mass, and cost. Microstrip array antennas provide an alternative option with lower cost; however they typically cannot achieve very high gains due to their feed network distribution losses. In recent years, microstrip reflectarray and transmitarray antennas have slowly emerged as the new generation of high-gain antennas, which combine many favorable features of reflectors, lenses and printed arrays. This new generation of high-gain antenna is low-profile, low-mass and low-cost, and therefore more suitable for deployment particularly for space applications.

Reflectarray antennas are similar in principal to parabolic reflectors, while the bulky curved surface of the parabolic reflector is replaced with a planar antenna array. Similarly, a transmitarray antenna is analogous to a lens antenna, where the bulky curved lens surface is replaced with a planar antenna array. These planar array configurations can be folded into small package designs that are easy to deploy and assemble in space. In addition to the desirable mechanical features for space applications, the most prominent feature of these antennas is the direct control of the phase of each element in the array. This unique feature can be utilized to achieve shaped or multiple beams with no additional cost, which is ideally desirable for many space antennas. In this work, the advantages and recent developments of reflectarray and transmitarray antennas for space applications will be reviewed. Several high-gain Ku- and Ka-band reflectarray and transmitarray antenna designs will be presented. Also prototypes demonstrating symmetric and asymmetric multi-beams, illustrating the beam-shaping capability of these arrays will be presented. Furthermore, recent developments in high-gain THz reflectarrays and transmitarrays will also be reviewed, and new dielectric type arrays utilizing an advanced 3-D fabrication technology will be demonstrated.
 

ABOUT THE SPEAKER
Atef Z. Elsherbeni received his Ph.D. degree in Electrical Engineering from Manitoba University, Winnipeg, Manitoba, Canada, in 1987. He joined the University of Mississippi in August 1987 as an Assistant Professor of Electrical Engineering. He advanced to the Associate Professor rank on July 1991, and to the Professor rank on July 1997. At the University of Mississippi, he was also the director of the School of Engineering CAD Lab from August 2002 to August 2013, the director of the Center for Applied Electromagnetic Systems Research (CAESR) from July 2011 to August 2013, and the Associate Dean of Engineering for Research and Graduate Programs from 2009 to 2013. He was appointed as Adjunct Professor, at The Department of Electrical Engineering and Computer Science of the L.C. Smith College of Engineering and Computer Science at Syracuse University on January 2004. He spent a sabbatical term in 1996 at the Electrical Engineering Department, University of California at Los Angeles (UCLA) and was a visiting Professor at Magdeburg University, in Germany during the summer of 2005 and at Tampere University of Technology in Finland during the summer of 2007. He was a Finland Distinguished Professor from 2009 to 2011. Dr. Elsherbeni became the Dobelman Distinguished Chair and Professor of Electrical Engineering and Computer Science at Colorado School of Mines in August 2013. He is a Fellow member of the Institute of Electrical and Electronics Engineers (IEEE) and a fellow member of The Applied Computational Electromagnetic Society (ACES) and the Editor-in-Chief for ACES Journal. 

REMARKS, IF ANY
 

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